Andrew j



(No Model.)

A. J. ALLEN 85 J. F. MORRISON.-

BRAKE SHOE.

No. 596,132. Patent-ed Dec. 28, 1897.

UNITED STATES PATENT since.

-ANDREW J. ALLEN AND JAMES F. MORRISON, OF CHICAGO, ILLINOIS.

BRAKE-SHOE.

SPECIFICATION forming part of Letters Patent I\To. 596,132, datedDecember 28, 1897.

Application filed May 29,1897. Serial No. 688,792. (No model.)

To mZZ whom; it may concern:

Be it known that we, ANDREW J. ALLEN and JAMES F. MORRISON, citizens ofthe United States, residing at Chicago, in the county of Cook and Stateof Illinois, have invented a certain new and useful Improvement inBrake-Shoes, (Case No; 1,) of which the following is a full, clear,concise, andexact description, reference being had to the accompanyingdrawings,forming a part of this specification.

Two typesof brake-shoes are well known in the artone, the compositeshoe, in the form of a shell, in which is placed a compound forming asurface which frictionally engages the wheel when the brake is applied.The other type has a frictional surface of an integral piece'formed inalternate sections of soft and chilled metal.

Our invention relates particularly to the first class of brake-shoes,and in its preferred embodiment has certain characteristics common tothe two types mentioned.

Heretofore a composition consisting of sawdust, comminuted iron,asbestos, plumbago, resin, and linseed-oil, thoroughly intermixed, hasbeen, among others, employed for the friction body of the shoe, suchcomposition being pressed within the shell either in a hot or coldcondition. The linseed-oil acted tobind the ingredients together. Thecomponent parts of the mass were thoroughly intermixed either in a hotor cold condition. If mixed in a hot condition, the carbonizableelements of the masswere frequently burn ed and partially reduced tocarbon, whereby the efficiency of the compound was greatly impaired, thefrictional character thereof being lessened,

' while the binder failed to properly perform gagement between the wheeland shoe as to cause the carbonization of the sawdust and linseed-oil,the subsequent disintegration of the body rapidly ensuing.

Compounds heretofore employed for brakeshoes were rigid and unyieldingto such a degree that a severe application of the brake would look thewheel and shoe together and cause the wheel to skid. v

Our invention consists in a composition for forming or partially formingthe surface of the brake-shoe, in the manner of manufacturing the saidcomposition, and in the particular combination of such composition withthe metal parts of the shoe.

The composition which we, have invented is composed, essentially, ofcomminuted iron, worked asphaltum, and Wahsatch rock, mixed together,preferably in the following manner and in substantially the proportionsnamed. The asphaltum is melted under a temperature of, say, 400Fahrenheit, and the comminuted iron, as iron chips or iron turnings, isthen mingled therewith, after which the Wahsatch rock in the form ofpowder is added, the entire mass being thoroughly commingled.

We have found that the best results are obtained by using eighteen partsof iron to one part of asphaltum and one part of Wallsatch rock, byweight.

The asphaltum acts as a binder and also imparts elasticity to thecomposition, while the Wahsatch rock counteracts this elasticity andalso acts to a certain extent as a binder.

The degree of elasticity and the coefficient of friction are governed bythe amount of the added Wahsatch rock.

'VVhere materials such as those we have specified are employed, the massis thoroughly coherent throughout, whereby a separation ordisintegration is impossible, and even though the heat generated byfriction in the application of the shoe to the wheel may be very greatthe only effect will be to make the friction body slightly more ductile,and this condition will exist only during the presence of the excessiveheat.

Our composition is such that granular particles are not formed betweenthe brake and the shoe, and the frictional engagement is slightlyyielding,so as to prevent the shoe from becoming rigidly clamped uponthe wheel to cause the same to skid.

Our composition when used in brakes applied to wheels having small holesor imperfections as it is worn off fills such holes or depressions asmay exist in the tread of the wheels, thus causing the wheels to conformto the outline of the working or frictional surface of the brake.

'We will describe the manner of compressing the composition into theiron shells of the shoe and the combination of the composition with theshell and the enlarged and taper chilled ends thereof in connection withthe accompanying drawings, in which- Figure 1 is aside view of the shellwith the frictional body. Fig. 2 is a front View thereof, and Fig. 3 isa cross-sectional View on line 3 3 of Fig. 1.

Like letters indicate like parts in the different views.

The shell a is provided with suitable eyes Z) 1), whereby it may beunited with the head of the shoe. The interior walls of the shell slopefrom the back to the front thereof, asis clearly indicated. Thecomposition dis forced within the shell under heavy pressure andpreferably while in a hot condition. The mass is thus solidified to therequired degree and firmly embedded within the shell. By tapering thewalls the dislodgment of the mass is prevented.

lVe preferably make the ends 0 c of the shell thick and chill the sameduring the process of casting. The ends are preferably taper chilled,diminishing from the place of greatest hardness at the front of the shoetoward the softness of the unehilled portion of the shell at the back ofthe shoe, as is indicated by the shading of the shell in Figs. 1 and 2.

The friction body in the newly-manufactured shoe preferably extendsbeyond the shell, as shown. As the body is worn down the hardestportions of the chilled ends are engaged by the wheel. As the brake-shoeis worn away the chilled ends thereof gradually become softer, while theengaged area of the frictional body gradually increases, the intentionbeing to have the resultant frictional effect of the chilled ends of theshoe and the frictional body maintained constant by thegradually-increasing frictional area of the body and thegradually-reduced hardness of the ends of the shoe as the shoe is wornaway.

Shoes made in accordance with our invention have an increase of lifefully thirty-five per cent. above that of any shoe now on the market.

Having thus described our invention, what We claim as new, and desire tosecure by Letters Patent, is-

1. A composition for brake-shoes, consisting of comminuted ironasphaltuin and Wahsatch rock intermixed in substantially the proportionsspecified.

2. The combination with the shell of a brake-shoe having enlarged taperchilled ends, the inner surfaces of the walls of the shell sloping fromthe back to the front thereof, of a composition contained within theshell comprising comminuted iron, asphaltum and Wahsatch rock intermixedin substantially the proportions specified.

3. The combination with the shell of a brake-shoe, having enlarged taperchilled ends, the inner surfaces of the walls of the shell sloping fromthe back to the front thereof, of a frictional body conforming to theinterior of the shell, the frictional area of the body being enlarged asthe shoe is worn away to compensate for the decreasing hardness of thechilled ends of the shoe.

'1. A composition for brake-shoes, consisting of comminuted iron,asphaltuin and an ingredient to counteract the elasticity of theasphaltum, substantially as described.

In witness whereof We hereunto subscribe our names this 25th day of May,A. D. 1897.

ANDREWV J. ALLEN. JAMES F. MORRISON. \Vitnesses:

GEORGE L. CRAGG, D. W. O. TANNER.

